diff --git a/src/qml/jsruntime/qv4function_p.h b/src/qml/jsruntime/qv4function_p.h
index 072c0fb9cc..67d31b6c6c 100644
--- a/src/qml/jsruntime/qv4function_p.h
+++ b/src/qml/jsruntime/qv4function_p.h
@@ -78,8 +78,8 @@ public:
 
     // first nArguments names in internalClass are the actual arguments
     Heap::InternalClass *internalClass;
-    uint nFormals;
     int interpreterCallCount = 0;
+    quint16 nFormals;
     bool isEval = false;
     bool detectedInjectedParameters = false;
 
diff --git a/src/qml/qml/qqmlpropertycache.cpp b/src/qml/qml/qqmlpropertycache.cpp
index e91148f66c..c7eed14593 100644
--- a/src/qml/qml/qqmlpropertycache.cpp
+++ b/src/qml/qml/qqmlpropertycache.cpp
@@ -743,13 +743,17 @@ QString QQmlPropertyCache::signalParameterStringForJS(QV4::ExecutionEngine *engi
     const QSet<QString> &illegalNames = engine->illegalNames();
     QString parameters;
 
-    for (int i = 0; i < parameterNameList.count(); ++i) {
+    const qsizetype count = parameterNameList.count();
+    if (count > std::numeric_limits<quint16>::max())
+        *errorString = QCoreApplication::translate("QQmlRewrite", "Signal has an excessive number of parameters: %1").arg(count);
+
+    for (qsizetype i = 0; i < count; ++i) {
         if (i > 0)
             parameters += QLatin1Char(',');
         const QByteArray &param = parameterNameList.at(i);
-        if (param.isEmpty())
+        if (param.isEmpty()) {
             unnamedParameter = true;
-        else if (unnamedParameter) {
+        } else if (unnamedParameter) {
             if (errorString)
                 *errorString = QCoreApplication::translate("QQmlRewrite", "Signal uses unnamed parameter followed by named parameter.");
             return QString();